Study On Ecological Security Evaluation Of Small Watersheds Based On Soil And Water Conservation In Mountainous Area Of Beijing

In recent years,the occurrence of rainstorm disasters in Beijing mountainous area reflects the lack of ecological security in mountainous area and threatens the economic development and the safety of residents' lives in Beijing.The treatment of soil and water conservation is an important way to improve the ecological environment in Beijing mountainous area.Therefore,it is of great significance to study the ecological security of small watershed in Beijing mountainous area.In this study,576 small Watersheds in Beijing mountain area are taken as the research object.In reference to the existing ecological safety assessment methods of soil and water conservation,the pressure-state-response(PSR)model is applied to analyze the ecological safety factors of soil and water conservation in the Beijing mountain area,and the evaluation index system of soil and water conservation ecological security of small watershed in mountainous area of Beijing is established.The index weight was determined by entropy weight method,and the ecological security status of small watershed in mountainous area of Beijing was evaluated based on grey relational analysis method.Five typical small watersheds are selected to analyze the change of ecological safety index.The results of this study show that:(1)On the time scale,during the period from 2012 to 2016 the ecological security index of small watershed in mountainous areas of Beijing had also increased with the increasing efforts of ecological clean watershed management in mountainous areas of Beijing.Although the ecological security index of some small watersheds has decreased due to external disturbance,the ecological security status of soil and water conservation in the small watershed of Beijing mountainous area showed an overall upward trend.The proportion of small watershed above the safety level in Beijing mountain area increased from 35.76%up to 52.26%.The proportion of small watershed in the relatively dangerous and dangerous levels decreased from 32.12%to 22.56%.(2)On the spatial scale,the distribution of the evaluation grades of the small watersheds in theBeijing mountainous area is relatively complex.The small watersheds which are in dangerous level in the evaluation of the small watersheds of soil and water conservation and ecological security are distributed in the east of Miyun area,the south of Mentougou and the middle of Huairou.The small watersheds which are in general level are widely distributed in the Beijing mountainous area,mainly in Huairou and Miyun.The small watersheds which are in relatively safe level and safe level are mainly distributed in the western part of the mountainous area and in most areas of Yanqing district.(3)According to the change of ecological safety index of soil and water conservation in small watershed in mountainous area of Beijing,it can be seen that the index of soil and water conservation is positively correlated with the intensity of soil and water conservation management.The work of soil and water conservation has achieved remarkable results after treatment and management in areas with better ecological environment.After the construction of soil and water conservation project,the ecological security situation of the small watershed with poor ecological environment has changed greatly,however,because of its weak ability to resist disasters,the treatment of soil and water conservation should be carried out continuously.The ecological security of untreated small watersheds is greatly affected by natural disasters,so we should strengthen the treatment of soil and water conservation.Finally,the evaluation results are verified according to the actual geological hazards.The results are basically consistent with the actual disasters,which indicates that the reliability of ecological security assessment results of small watershed in Beijing mountainous area is high.